This study is a Canadian multicentre randomized, double-blind placebo controlled trial. We will evaluate whether prophylactic citalopram compared to symptomatic treatment of depression can significantly increase the amount of HCV therapy received in co-infected patients during the first 24 weeks. Post study follow-up will extend until 6 months after cessation of HCV therapy (up to 72 weeks) to capture information on SVR (sustained virologic response) for HCV. 76 patients will be randomized in a 1:1 ratio to citalopram or placebo. Patients will be stratified by study centre and HCV genotype. Citalopram (or placebo) will begin 3 weeks before HCV treatment at an initial dose of 10 mg per day then be increased to 20 mg per day after one week and continued throughout treatment with PEG-IFN/ribavirin (up to 48 weeks) and then tapered to discontinuation at completion of HCV therapy. The management of depression emerging in study participants is mandated in the protocol to ensure that the original treatment assignments remain blinded while allowing for all subjects to remain in the study and mimics what would take place in clinical practice.